Keiichi Tsutsui

Over 15-GB Capacity Domain Wall Displacement Detection Magneto Optical Recording Using a Digital Versatile Disc Dimensional Optical Head.

High-density magneto-optical (MO) recording using a land/groove structured domain wall displacement detection (DWDD) medium has been achieved with a digital versatile disc (DVD) dimensional optical head including a 664-nm wavelength laser diode and a 0.60-NA objective lens. Due to the deep groove depth, easy domain wall displacement is obtained without the use of a track boundary postannealing process. Sufficient readout performance is obtained in experiments at an areal recording density of 11 Gbit/inch2, which is obtained using a 0.13-µm bit length and a 0.45-µm track pitch. This areal density corresponds to a capacity of 15 GB per one 120-mm-diameter disk.

A cross point Cu-ReRAM with a novel OTS selector for storage class memory applications

This paper demonstrates a cross point Cu based Resistive Random Access Memory (Cu-ReRAM) technology suitable for Storage Class Memory (SCM) applications. Two key technologies have been developed for large capacity of 100Gb-class SCM with 100 ns program speed and 10M cycles of program endurance. One is tight resistance distributions of Cu-ReRAM by inserting a barrier layer to prevent excess intermixing. The other is a novel Boron and Carbon (BC) based Ovonic Threshold Switch (OTS) selector which meets requirements for large cross point arrays with low leakage current, low threshold voltage variability, and high endurance.

Optical card tracking servo system utilizing two light sources

We have developed optical card tracking servo system utilizing two light sources which is highly effective for reading/writing data on dirty or optical card.

Greater than 15-GB-capacity DWDD-MO recording using a DVD dimensional optical head

A new class of super resolution method was proposed for magneto-optical recording by T. Shiratori et.al. The method called DWDD (Domain Wall Displacement Detection) is principled on momentary magnetic wall displacement during a read-out.

A Write-Once Optical Card Reader/Writer Using Two Optical Sources

An optical card has many advantages such as portability, large storage capacity, and low cost. We have developed an optical card reader/writer using two optical sources: a laser diode (LD) for writing and an LED for reading. We have demonstrated that this method is effective for stable and high speed reading/writing because of (1) wide tracking dynamic range, (2) stable data reading signal vs. tracking error, (3) no card damage by reading light, (4) two track reading, and (5) direct read during write.